In a three-dimensional (3D) television (TV) system, images displayed to an left eye and an right eye of a user are different, therefore, backlight dimming for displaying a three-dimensional (3D) signal is different with backlight-dimming for displaying a two-dimensional (2D) signal.
As shown FIG. 1, in a TV system, a motherboard 5 sends a 3D signal to a TV control board 2, and the TV control board 2 controls a converter 3 to dim in accordance with a defined DUTY and DELAY signal after the TV control board 2 receives the 3D signal. At this moment, both current and voltage of a light bar 4 (light source) change suddenly, and the converter 3 and a power board 1 both require a dynamic response speed to meet a momentary load change (the current and voltage change of the tight bar). However, the entire power system is instable and oscillates if the response speed is blindly adjusted. Therefore, the response speed of the entire power system needs to be faster in another mode.